Method of forming golf club head assembly

ABSTRACT

A method of forming a golf club head assembly includes aligning a faceplate with a recess of a club head; welding the faceplate to the club head; then, after welding the faceplate, heating the club head and the faceplate to at least a solvus temperature of the faceplate for a predetermined amount of time; and then, after heating the club head and the faceplate, allowing the club head and the faceplate to air cool.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a non-provisional of U.S. Provisional Patent Application No.61/941,117, filed on Feb. 18, 2014, and is a continuation-in-part ofU.S. patent application Ser. No. 14/228,503, filed on Mar. 28, 2014, theentire contents of all of the above are fully incorporated herein byreference.

BACKGROUND

The present invention relates to golf clubs and particularly to a methodof forming a golf club head assembly.

Conventional golf club head assemblies include a faceplate welded to aclub head. The faceplate has a slightly rounded shape in order toprovide a straighter and/or longer flight path for a golf ball, evenwhen the ball is struck off-center with respect to the faceplate. Thefaceplate has a bulge dimension, or curvature from a toe end to a heelend, and a roll dimension, or curvature from the crown edge to the soleedge.

Aspects of the invention will become apparent by consideration of thedetailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a club head and a face plate.

FIG. 2 is a perspective view of the club head with the face plateremoved.

FIG. 3 is a top view of a club head assembly.

FIG. 4 is a side section view of the club head assembly of FIG. 3 alongsection 4-4.

FIG. 5 is a side view of the club head assembly of FIG. 3.

FIG. 6 is a schematic view of a process for forming a golf club headassembly.

FIG. 7 is a chart showing experimental bulge and roll measurements forfaceplates that are subjected to various heat-treatment processes.

FIG. 8 is a chart showing experimental roll measurements for faceplateshaving various geometries.

FIG. 9 is a chart showing experimental bulge and roll measurements forfaceplates that are subjected to various heat-treatment processes.

FIG. 10. is a chart showing durability measurements for faceplateshaving various material compositions.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” and “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. All weight percent (wt %) numbers describedbelow are a total weight percent.

DETAILED DESCRIPTION

FIG. 1-3 shows a golf club head 10 and a faceplate 14. In oneembodiment, the golf club head 10 is formed from a cast material and thefaceplate 14 is formed from a rolled material. Further, in theillustrated embodiment, the golf club head 10 is for a metal wooddriver; in other embodiments, the golf club head 10 is for a fairwaywood; in other embodiments, the golf club head 10 is for hybrid clubs;in other embodiments, the golf club head 10 is for an iron club. Theclub head 10 may also include a hosel and a hosel transition (shown as18). For example, the hosel may be located at or proximate to the heelend 34. The hosel may extend from the club head 10 via the hoseltransition 18. To form a golf club, the hosel may receive a first end ofa shaft 20. The shaft 20 may be secured to the golf club head 10 by anadhesive bonding process (e.g., epoxy) and/or other suitable bondingprocesses (e.g., mechanical bonding, soldering, welding, and/orbrazing). Further, a grip (not shown) may be secured to a second end ofthe shaft 20 to complete the golf club.

As shown in FIG. 2, the club head 10 further includes a recess oropening 22 for receiving the faceplate 14. In the illustratedembodiment, the opening 22 includes a lip 26 extending around theperimeter of the opening 22. The faceplate 14 is aligned with theopening and abuts the lip 26. The faceplate 14 is secured to the clubhead 10 by welding, forming a club head assembly 30. In one embodiment,the welding is a pulse plasma welding process.

The faceplate 14 includes a heel end 34 and a toe end 38 opposite theheel end 34. The heel end 34 is positioned proximate the hosel portion(hosel and hosel transition 18) where the shaft 20 (FIG. 1) is coupledto the club head assembly 30. The faceplate 14 further includes a crownedge 42 and a sole edge 46 opposite the crown edge 42. The crown edge 42is positioned adjacent an upper edge of the club head 10, while the soleedge 46 is positioned adjacent the lower edge of the club head 10. Asshown in FIG. 3, the faceplate 14 has a bulge curvature in a directionextending between the heel end 34 and the toe end 38. As shown in FIGS.4 and 5, the faceplate 14 also has a roll curvature in a directionextending between the crown edge 42 and the sole edge 46. In oneembodiment, the faceplate may have a minimum wall thickness of 1.5millimeters, 1.4 millimeters, 1.3 millimeters, 1.2 millimeters, 1.1millimeters, 1.0 millimeters, 0.9 millimeters, 0.8 millimeters, 0.7millimeters, 0.6 millimeters, 0.5 millimeters and 0.4 millimeters. Inone embodiment, the faceplate may have a minimum wall thickness of 0.7millimeters.

The faceplate 14 is formed from a titanium alloy. In one embodiment, thefaceplate 14 is an α-β titanium (α-β Ti) alloy. The α-β Ti alloy maycontain neutral alloying elements such as tin and a stabilizers such asaluminum and oxygen. The α-β Ti alloy may contain β-stabilizers such asmolybdenum, silicon and vanadium. All numbers described below regardingweight percent are a total weight percent (wt %). The total weightpercent of α-stabilizer aluminum in α-β Ti alloy may be between 2 wt %to 10 wt %, 3 wt % to 9 wt %, 4 wt % to 8 wt %, or 5 wt % to 7 wt %. Thetotal weight percent of α-stabilizer oxygen in α-β Ti alloy may bebetween 0.05 wt % to 0.35 wt %, or 0.10 wt % to 0.20 wt %. The totalweight percent of β-stabilizer molybdenum in α-β Ti alloy may be between0.2 wt % to 1.0 wt %, or 0.6 wt % to 0.8 wt %, or trace amounts. Thetotal weight percent of β-stabilizer vanadium in α-β Ti alloy may bebetween 1.5 wt % to 7 wt %, or 3.5 wt % to 4.5 wt %. The total weightpercent of β-stabilizer silicon in α-β Ti alloy may be between 0.01 to0.10 wt %, or 0.03 wt % to 0.07 wt %. The α-β Ti alloy may be Ti-6Al-4V(or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI550. The combination of α, β stabilizers allows the α-β Ti alloys to beheat treated.

In one embodiment, after welding the faceplate 14 to the club head 10,the club head 10 and faceplate 14 may be heated to a temperature at,just above, or greater than the solvus temperature of the faceplate fora predetermined amount of time. In another embodiment, after welding thefaceplate 14 to the club head 10, the club head assembly 30 may be heattreated at a temperature at, just above or greater than the α-β Tisolvus temperature for a predetermined amount of time. In anotherembodiment, after welding the faceplate 14 to the club head 10, the clubhead assembly 30 may be heat treated at a temperature at, just above orgreater than the α-β Ti solvus temperature for a predetermined amount oftime. Also, during this step, an inert gas may be pumped into theheating chamber housing the club head assembly 30 to remove all oxygenover a predetermined amount of time discussed below. Upon cooling of theclub head assembly 30 as discussed below, additional inert gas may bepumped back into the chamber where the club head assembly 30 is allowedto cool to room temperature.

As discussed above, after heating the club head assembly 30 (or the clubhead 10 and the welded faceplate 14), the club head assembly 30 isallowed to cool to room temperature. In another embodiment, after theheat treatment, the club head assembly 30 may be allowed to air cool toslowly reduce the club head assembly's temperature. The cooling of theclub head assembly 30 may be done in an inert gas environment ornon-contained environment (open air). In another embodiment, the clubhead assembly 30 may be allowed to cool in inert gas to slowly reducethe club head assembly's temperature and reduce chance for oxidation.The inert gas may be selected from the group consisting of nitrogen (N),argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe) or acompound gas thereof. After heating to, just above, or greater than theα-β Ti solvus temperature, inert gas may be pumped back into a chamberunder vacuum housing the club assembly 30, which ensures no oxygen ispresent to prevent oxidation to the titanium faceplate 14 and club headsurfaces 10.

As understood by a person of ordinary skill, the solvus temperature foran alloy is the temperature barrier at which smaller constituentmolecules dissolve within the general matrix of the material and becomemore mobile. The solvus temperatures of most α-β Ti alloys are verifiedand readily available in academic literature or information published bymaterial suppliers. If published data is unavailable, the temperaturevalues can be estimated and experimentally confirmed, since it isdependent on the material's chemistry. The solvus temperature for α-β Tican be above 400° C. and below 600° C.

In one embodiment, the α-β Ti may be Ti 6-4 containing 6 wt % aluminum(Al), and 4 wt % vanadium (V), with the remaining alloy compositionbeing titanium and possibly some trace elements. In some embodiments, Ti6-4 contains between 5.5 wt %-6.75 wt % Al, between 3.5 wt %-4.5 wt % V,a maximum of 0.08 wt % carbon (C), a maximum of 0.03 wt % silicon (Si),a maximum of 0.3 wt % iron (Fe), a maximum of 0.2 wt % oxygen (O), amaximum of 0.015 wt % tin (Sn), and trace amounts of molybedenum (Mo),with the remaining alloy composition being titanium. In someembodiments, Ti 6-4 contains between 5.5 wt %-6.75 wt % Al, between 3.5wt %-4.5 wt % V, 0.08 wt % or less carbon (C), 0.03 wt % or less silicon(Si), 0.3 wt % or less iron (Fe), 0.2 wt % or less oxygen (O), 0.015 wt% or less tin (Sn), and trace amounts of molybedenum (Mo), with theremaining alloy composition being titanium. Ti 6-4 is a grade 5titanium. The solvus temperature for Ti 6-4 is between 540° C. and 560°C. In some embodiments, Ti 6-4 has a density of 0.1597 lb/in³ (4.37g/cc). Ti-6-4 may also be designated as T-65K.

In other embodiments, the faceplate 14 of the golf club head 10 may beanother α-β Ti alloy, such as Ti-9S (or T-9S), which contains 8 wt % Al,1 wt % V, and 0.2 wt % Si, with the remaining alloy composition beingtitanium and possibly some trace elements. In some embodiments, Ti-9S(or T-9S) contains 6.5 wt %-8.5 wt % Al, between 1 wt %-2 wt % V, amaximum of 0.08 wt % C, a maximum of 0.2 wt % Si, a maximum of 0.3 wt %Fe, a maximum of 0.2 wt % O, a maximum of 0.05 wt % N, trace amounts ofMo, and trace amounts of Sn, with the remaining alloy composition beingtitanium. In some embodiments, Ti-9S (or T-9S) contains 6.5 wt %-8.5 wt% Al, between 1 wt %-2 wt % V, less than 0.1 wt % C, a maximum of 0.2 wt% Si, a maximum of 0.4 wt % Fe, a maximum of 0.15 wt % O, less than 0.05wt % N, trace amounts of Mo, and trace amounts of Sn, with the remainingalloy composition being titanium. In some embodiments, Ti-9S (or T-9S)contains 6.5 wt %-8.5 wt % Al, between 1 wt %-2 wt % V, 0.1 wt % or lessC, 0.2 wt % or less Si, 0.4 wt % or less Fe, 0.15 wt % or less O, lessthan 0.05 wt % N, trace amounts of Mo, and trace amounts of Sn, with theremaining alloy composition being titanium. The solvus temperature forTi-9S (or T-9S) is between 560° C. and 590° C. In some embodiments, theTi-9S (or T-9s) will have higher porosity and a lower yield than Ti8-1-1. Ti-9S (or T-9S) has a density of about 0.156 lb/in³ to 0.157lb/in³ (4.32-4.35 g/cc). Ti-9S (or T-9S) has a density of 0.156 lb/in³(4.32 g/cc).

In other embodiments, the material may be another α-β Ti alloy, such asTi-6-6-2, Ti-6246, or IMI 550. Titanium 662 may contain 6 wt % Al, 6 wt% V, and 2 wt % Sn, with the remaining alloy composition being titaniumand possibly some trace elements. Ti-6-6-2 has a density of 0.164 lb/in3(4.54 g/cc). The solvus temperature for Ti 662 is between 540° C. and560° C. Titanium 6246 may contain 6 wt % Al, 2 wt % Sn, 4 wt % zirconium(Zr), and 6 wt % Mo, with the remaining alloy composition being titaniumand possibly some trace elements. The solvus temperature for Ti 6246 isbetween 570° C. and 590° C. Ti-6246 has a density of 0.168 lb/in3 (4.65g/cc). IMI 550 may contain 6 wt % Al, 2 wt % Sn, 4 wt % Mo, and 0.5 wt %Si, with the remaining alloy composition being titanium and possiblysome trace elements. The solvus temperature for IMI 550 is between 490°C. and 510° C. IMI 550 has a density of 0.157 lb/in³ (4.60 g/cc).

In other embodiments, the material may be another α-β Ti alloy, such asTi-8-1-1, which may contain 8 wt % Al, 1.0 wt % Mo, and 1 wt % V, withthe remaining alloy composition being titanium and possibly some traceelements. In some embodiments, Ti-8-1-1 may contain 7.5 wt %-8.5 wt %Al, 0.75 wt %-1.25 wt % Mo., 0.75 wt %-1.25 wt % V, a maximum of 0.08 wt% C, a maximum of 0.3 wt % Fe, a maximum of 0.12 wt % O, a maximum of0.05 wt % N, a maximum of 0.015 wt % H, a maximum of 0.015 wt % Sn, andtrace amounts of Si, with the remaining alloy composition beingtitanium. The solvus temperature for Ti-8-1-1 is between 560° C. and590° C. In some embodiments, Ti-8-1-1 has a density of 0.1580 lb/in³(4.37 g/cc).

FIG. 6 shows the process for forming for the club head assembly 30. Inthe first step 62, the faceplate 14 is aligned with respect to the clubhead 10. The second step 66 involves welding the faceplate 14 to theclub head 10. In the third step 70, the club head 10 and the faceplate14 are heated to a temperature at or above the solvus temperature of thefaceplate 14 material. Finally, in the fourth step 74 the club head 10and the faceplate 14 are air cooled.

In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forbetween 1 hour and 6 hours in the third step 70. In one embodiment, theclub head assembly 30 is heat treated at a temperature at or above thesolvus temperature of the α-β Ti alloy for between 1 hour and 2 hours inthe third step 70. In one embodiment, the club head assembly 30 is heattreated at a temperature at or above the solvus temperature of the α-βTi alloy for between 1 hour and 4 hours in the third step 70. In oneembodiment, the club head assembly 30 is heat treated at a temperatureat or above the solvus temperature of the α-β Ti alloy for between 4hours and 6 hours in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for between 1.5 hours and 5.5 hours inthe third step 70. In one embodiment, the club head assembly 30 is heattreated at a temperature at or above the solvus temperature of the α-βTi alloy for between 2 hours and 5 hours in the third step 70. In oneembodiment, the club head assembly 30 is heat treated at a temperatureat or above the solvus temperature of the α-β Ti alloy for between 2.5hours and 4.5 hours in the third step 70. In one embodiment, the clubhead assembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for between 3 hours and 4 hours in thethird step 70.

In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 1 hour in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for at least 1.5 hours in the third step70. In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 2 hours in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for at least 2.5 hours in the third step70. In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 3 hours in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for at least 3.5 hours in the third step70. In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 4 hours in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for at least 4.5 hours in the third step70. In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 5 hours in the third step 70. In one embodiment, the club headassembly 30 is heat treated at a temperature at or above the solvustemperature of the α-β Ti alloy for at least 5.5 hours in the third step70. In one embodiment, the club head assembly 30 is heat treated at atemperature at or above the solvus temperature of the α-β Ti alloy forat least 6 hours in the third step 70.

In one embodiment, the club head assembly 30 is heat treated between400° C. and 630° C. in the third step 70. In one embodiment, the clubhead assembly 30 is heat treated between 425° C. and 550° C. In oneembodiment, the club head assembly 30 is heat treated between 450° C.and 525° C. in the third step 70. In one embodiment, the club headassembly 30 is heat treated between 550° C. and 625° C. in the thirdstep 70. In one embodiment, the club head assembly 30 is heat treated at400° C., 410° C., 420° C., 430° C., 440° C., 450° C., 460° C., 470° C.,480° C., 490° C., 500° C., 510° C., 520° C., 530° C., 540° C., 550° C.,560° C., 570° C., 580° C., 590° C., 600° C., 610° C., 620° C., or 630°C. in the third step 70 for 30 minutes, 60 minutes, 90 minutes, 120minutes, 150 minutes, 180 minutes, 210 minutes, 240 minutes, 270minutes, 300 minutes, 330 minutes or 360 minutes.

In one embodiment, the club head assembly 30 is heat treated at atemperature of at least 400° C. in the third step 70. In one embodiment,the club head assembly 30 is heat treated at a temperature of at least420° C. in the third step 70. In one embodiment, the club head assembly30 is heat treated at a temperature of at least 440° C. in the thirdstep 70. In one embodiment, the club head assembly 30 is heat treated ata temperature of at least 460° C. in the third step 70. In oneembodiment, the club head assembly 30 is heat treated at a temperatureof at least 475° C. in the third step 70. In one embodiment, the clubhead assembly 30 is heat treated at a temperature of at least 480° C. inthe third step 70. In one embodiment, the club head assembly 30 is heattreated at a temperature of at least 500° C. in the third step 70. Inone embodiment, the club head assembly 30 is heat treated at atemperature of at least 520° C. in the third step 70. In one embodiment,the club head assembly 30 is heat treated at a temperature of at least540° C. in the third step 70. In one embodiment, the club head assembly30 is heat treated at a temperature of at least 560° C. in the thirdstep 70. In one embodiment, the club head assembly 30 is heat treated ata temperature of at least 575° C. in the third step 70. In oneembodiment, the club head assembly 30 is heat treated at a temperatureof at least 580° C. In one embodiment, the club head assembly 30 is heattreated at a temperature of at least 600° C. in the third step 70. Inone embodiment, the club head assembly 30 is heat treated at atemperature of at least 620° C. in the third step 70. In one embodiment,the club head assembly 30 is heat treated at a temperature of at least625° C. in the third step 70. In one embodiment, the club head assembly30 is heat treated at a temperature of at least 630° C. in the thirdstep 70.

In one embodiment, the club head assembly 30 is heat treated between475° C. and 500° C. for between 4 hours and 6 hours in the third step70. In another embodiment, the club head is heat treated between 575° C.and 625° C. for between 1 hour and 2 hours in the third step 70. Inanother embodiment, the club head is heat treated at about 550° C. forbetween 1 hour and 4 hours. In other embodiments, the face plate 14 maybe formed from a different alloy in the third step 70. In otherembodiments, the heat treatment process may be implemented at othertemperatures for a different amount of time. In addition, the heattreatment may be applied to a variety of materials and a variety ofweld-types.

Unlike conventional club head metal aging processes that occur at lowtemperature, heat-treating the club head assembly 30 above the solvustemperature after welding the faceplate 14 relieves stresses in thefaceplate 14 and between the weld and the metal matrix of the club head10. The post-weld stress relief disperses stresses associated with theweld-metal heat affected zone (HAZ), or the area around the weld inwhich the material properties have been altered due to the weldingprocess. Because of the stark contrast in mechanical properties betweenthe HAZ and the rest of the metal matrix, the HAZ is much more likely toexperience a crack and fail. Previous post-weld treatments wereperformed below the solvus temperature for a short duration of time.These processes simply aged the metals, but did not address theincreased stresses transferred to the weld area. Furthermore, thefaceplate was not sufficiently strong and would flatten or lose itscurvature relatively quickly. In contrast, the heat treatment above thesolvus temperature disperses stresses in the weld metal HAZ. Theheat-treatment improves the durability of the HAZ by relieving thestresses. In addition, heat-treating the club head assembly 30 above thesolvus temperature reduces the possibility of generatingtitanium-aluminum (Ti₃Al) crystals along the weld.

The grains of the faceplate alloy may be aligned in a crown to soleorientation prior to heat treating. The crown to sole orientation of thealloy grains permits stretching in the same direction. In someembodiments, the grains of the faceplate α-β titanium (α-β Ti) alloy maybe aligned in a crown to sole orientation prior to heat treating. Thecrown to sole orientation of the α-β Ti alloy grains permits stretchingin the same direction. In some embodiments, the grains of the faceplateTi-6Al-4V (or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K,Ti-6246, or IMI 550 alloy may be aligned in a crown to sole orientationprior to heat treating. The crown to sole orientation of the Ti-6Al-4V(or Ti 6-4), Ti-9S (or T-9S), Ti-662, Ti-8-1-1, Ti-65K, Ti-6246, or IMI550 alloy grains permits stretching in the same direction.

The heat treatment also improves the strength of the faceplate 14. Theimproved strength permits the faceplate 14 to be made thinner withoutsacrificing durability, thereby reducing club head weight. The reducedweight of faceplate 14 shifts the center of gravity of the club headassembly 30, and allows additional weight to be added to anothercomponent of the club to further adjust the center of gravity.Increasing the strength of the faceplate 14 also increases thedurability of the faceplate 14, which permits the faceplate 14 to endurea significantly higher number of hits against a golf ball and maintainthe faceplate's slightly bowed or rounded shape over the life of theclub while sustaining hundreds or thousands of golf ball strikes.Therefore, the club is more forgiving when a ball is struck off-centerbecause the rounded shape of the faceplate 14 provides a “gear effect”between the ball and faceplate 14.

As shown in FIG. 7, an experiment was performed to compare the effect ofvarious heat treatment temperatures on the faceplate 14 over the courseof 2,000 hits or ball strikes. The faceplates 14 were formed from Ti-9S(or T-9S) alloy. One club head assembly was heated to 400° C., which isbelow the solvus temperature of the Ti-9S (or T-9S) alloy. A second clubhead assembly was heated to 600° C., which is above the solvustemperature of the Ti-9S (or T-9S) alloy. The measurement data providedin FIG. 7 represent the percent change in the radius of curvature of thebulge and the roll dimensions compared to the original radius curvature.As the faceplate becomes more flat, the radius of curvature increases.The club head assembly having a faceplate 14 with Ti-9S treated at 400°C. flattened significantly in both its roll and bulge dimensions within25 hits on a golf ball. In contrast, the club head assembly having aTi-9S faceplate treated at 600° C. maintained its curvaturesignificantly better than the first club head assembly after 2,000 hits.The Ti-9S faceplate treated at 600° C. maintained its' curvature betterafter 2000 hits than the first club head assembly having a faceplate 14of Ti-6-4 untreated maintained curvature in both roll and bulgedimensions.

For heat treatments below the solvus temperature (for example, at 400°C.), Ti₃Al particles become more mobile and can precipitate into theα-matrix. Some of the Ti₃Al particles gather at grain boundaries and ageharden the material. In contrast, for heat treatments above the solvustemperature (for example, at 600° C.), Ti₃Al particles instead dissolvewithin the α-matrix and relieve stresses within the material. The stressrelief processes enables the club head assembly 30 to withstand tensileand compressive forces during impact against a golf ball.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 2 wt % of its original bulge and roll curvature after about 25strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within 3wt % of its original roll curvature and within 8 wt % of its originalbulge curvature after about 25 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 8 wt % of its original bulge and roll curvature after about 50strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within 5wt % of its original roll curvature and within 10 wt % of its originalbulge curvature after about 50 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about 75strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within13 wt % of its original roll curvature and within 10 wt % of itsoriginal bulge curvature after about 75 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about 100strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within14 wt % of its original roll curvature and within 10 wt % of itsoriginal bulge curvature after about 100 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about 150strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within15 wt % of its original roll curvature and within 11 wt % of itsoriginal bulge curvature after about 150 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about 300strikes. In one embodiment, the faceplate 14 that is formed from Ti 6-4and heat treated above the solvus temperature of Ti 6-4 remains within15 wt % of its original roll and bulge curvature after about 300strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about1,000 strikes. In one embodiment, the faceplate 14 that is formed fromTi 6-4 and heat treated above the solvus temperature of Ti 6-4 remainswithin 23 wt % of its original roll curvature and within 17 wt % of itsoriginal bulge curvature after about 1,000 strikes.

In one embodiment, the faceplate 14 that is formed from Ti-9S (or T-9S)and heat treated above the solvus temperature of Ti-9S (or T-9S) remainswithin 10 wt % of its original bulge and roll curvature after about2,000 strikes. In one embodiment, the faceplate 14 that is formed fromTi 6-4 and heat treated above the solvus temperature of Ti 6-4 remainswithin 24 wt % of its original roll curvature and within 18 wt % of itsoriginal bulge curvature after about 2,000 strikes.

Furthermore, an experiment was performed to compare the effect ofvarious heat treatment temperatures on the faceplate 14 over the courseof 2,000 hits or ball strikes. The faceplate 14 was formed from α-β Tialloy. One club head assembly was heated to 400° C., which is below thesolvus temperature of the α-β Ti alloy. A second club head assembly washeated to 600° C., which is above the solvus temperature of the α-β Tialloy. The club head assembly treated at 400° C. flattened significantlyin both its roll and bulge dimensions within 25 hits on a golf ball. Incontrast, the club head assembly treated at 600° C. did not begin toflatten until 225 strikes on a golf ball and maintained its curvaturesignificantly better than the first club head assembly after 2,000 hits.

In one embodiment, the club head assembly treated at 600° C. maintainedits original bulge and roll curvature after 25 hits. In one embodiment,the club head assembly treated at 600° C. maintained its original bulgeand roll curvature after 50 hits. In one embodiment, the club headassembly treated at 600° C. maintained its original bulge and rollcurvature after 75 hits. In one embodiment, the club head assemblytreated at 600° C. maintained its original bulge and roll curvatureafter 100 hits. In one embodiment, the club head assembly treated at600° C. maintained its original bulge and roll curvature after 125 hits.In one embodiment, the club head assembly treated at 600° C. maintainedits original bulge and roll curvature after 150 hits. In one embodiment,the club head assembly treated at 600° C. maintained its original bulgeand roll curvature after 175 hits. In one embodiment, the club headassembly treated at 600° C. maintained its original bulge and rollcurvature after 200 hits. In one embodiment, the club head assemblytreated at 600° C. maintained its original bulge and roll curvatureafter 225 hits.

In one embodiment, the club head assembly treated at 600° C.substantially maintained its bulge and roll curvature after 250 hits. Inone embodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 275 hits. In oneembodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 300 hits. In oneembodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 500 hits. In oneembodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 1,000 hits. In oneembodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 1500 hits. In oneembodiment, the club head assembly treated at 600° C. substantiallymaintained its bulge and roll curvature after 2,000 hits.

In one embodiment, the club head assembly treated at 600° C. maintainedits original bulge curvature and its roll curvature radius increasedfrom 11 inches to 13 inches after 250 hits. In one embodiment, the clubhead assembly treated at 600° C. maintained its original bulge curvatureand maintained a roll curvature radius of 13 inches after 275 hits. Inone embodiment, the club head assembly treated at 600° C. increased itsbulge curvature radius from 12 inches to 13 inches and maintained a rollcurvature radius of 13 inches after 300 hits. In one embodiment, theclub head assembly treated at 600° C. maintained its bulge curvatureradius of 13 inches and maintained a roll curvature radius of 13 inchesafter 500 hits. In one embodiment, the club head assembly treated at600° C. maintained its bulge curvature radius of 13 inches and increasedits roll curvature radius from 13 inches to 14 inches after 1,000 hits.In one embodiment, the club head assembly treated at 600° C. maintainedits bulge curvature radius of 13 inches and maintained a roll curvatureradius of 14 inches after 1,500 hits. In one embodiment, the club headassembly treated at 600° C. maintained its bulge curvature radius of 13inches and maintained a roll curvature radius of 14 inches after 2,000hits.

Also, as shown in FIG. 8, a follow-up experiment was performed tocompare the impact of a 600° C. heat treatment on three differentfaceplate geometries. The roll measurements for all three faceplategeometries were consistent, confirming that the stress-relief heattreatment increases the faceplate's ability to maintain its curvature.The faceplate comprised the Ti-9S (or T-9S) alloy.

Referring now to FIG. 9, an experiment was performed to compare theeffect of various heat treatment temperatures on the faceplate 14 overthe course of 2,000 hits or ball strikes. The faceplates 14 were formedfrom Ti-9S (or T-9S) alloy. One club head assembly was heated to 550°C., which is below the solvus temperature of the Ti-9S (or T-9S) alloy.A second club head assembly was heated to 575° C. and a third club headwas heated to 600° C., which is above the solvus temperature of theTi-9S (or T-9S) alloy. The measurement data provided in FIG. 9 representthe percentage change in the radius of curvature of the bulge and theroll dimensions compared to the original radius curvature. As thefaceplate becomes more flat, the radius of curvature increases. The clubhead assembly treated at 550° C. flattened significantly in both itsroll and bulge dimensions within a few hits on a golf ball. In contrast,the club head assembly treated at 600° C. maintained its curvaturesignificantly better than the club head assemblies after 2,000 hits.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. remains within 1 wt % of its original roll curvatureand within 3 wt % of its original bulge curvature after 25 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 24 wt % of its original roll curvatureand within 11 wt % of its original bulge curvature after 25 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 19 wt % of its original roll curvatureand within 9 wt % of its original bulge curvature after 25 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. retains its original roll curvature and is within 4wt % of its original bulge curvature after 50 strikes. In oneembodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 28 wt % of its original roll curvatureand within 13 wt % of its original bulge curvature after 50 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 23 wt % of its original roll curvatureand within 15 wt % of its original bulge curvature after 50 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. retains its original roll curvature and is within 5wt % of its original bulge curvature after 75 strikes. In oneembodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 28 wt % of its original roll curvatureand within 12 wt % of its original bulge curvature after 75 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 28 wt % of its original roll curvatureand within 23 wt % of its original bulge curvature after 75 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. retains its original roll curvature and is within 6wt % of its original bulge curvature after 100 strikes. In oneembodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 30 wt % of its original roll curvatureand within 13 wt % of its original bulge curvature after 100 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 29 wt % of its original roll curvatureand within 22 wt % of its original bulge curvature after 100 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. retains its original roll curvature and is within 7wt % of its original bulge curvature after 150 strikes. In oneembodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 28 wt % of its original roll curvatureand within 13 wt % of its original bulge curvature after 150 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 31 wt % of its original roll curvatureand within 24 wt % of its original bulge curvature after 150 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. remains within 5 wt % of its original roll curvatureand within 5 wt % of its original bulge curvature after 300 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 28 wt % of its original roll curvatureand within 14 wt % of its original bulge curvature after 300 strikes. Inone embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 34 wt % of its original roll curvatureand within 26 wt % of its original bulge curvature after 300 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. remains within 4 wt % of its original roll curvatureand within 7 wt % of its original bulge curvature after 1,000 strikes.In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 27 wt % of its original roll curvatureand within 13 wt % of its original bulge curvature after 1,000 strikes.In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 34 wt % of its original roll curvatureand within 27 wt % of its original bulge curvature after 1,000 strikes.

In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 600° C. remains within 5 wt % of its original roll curvatureand within 6 wt % of its original bulge curvature after 2,000 strikes.In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 575° C. remains within 25 wt % of its original roll curvatureand within 15 wt % of its original bulge curvature after 2,000 strikes.In one embodiment, the faceplate 14 formed from Ti-9S (or T-9S) and heattreated at 550° C. remains within 34 wt % of its original roll curvatureand within 28 wt % of its original bulge curvature after 2,000 strikes.

As shown in FIG. 10, an experiment was performed to compare thedurability of faceplate 14 when composed of either the Ti-6-4 alloy orthe Ti-9S (T-9S) alloy. The experiment tracked the number of strikesfrom an air cannon until failure of the faceplate 14. One club headassembly used Ti 6-4 alloy as the faceplate material. A second club headassembly used a different model club head with Ti 6-4 alloy as thefaceplate material (data not shown). A third club head assembly used athird model club head with the Ti 6-4 alloy as the faceplate material(data not shown). A fourth club head assembly uses the same model clubhead as the third club head assembly, with T-9S (or Ti-9S) alloy as thefaceplate material. The measurement data provided in FIG. 10 representsthe number of hits until failure of the faceplate. The club headassembly with the T-9S (or Ti-9S) alloy faceplate showed increaseddurability over assemblies with Ti 6-4 alloy faceplates. The same clubhead model showed an increased durability of about 3200 hits untilfailure of the faceplate with T-9S (or Ti-9S) alloy as the faceplatematerial, as opposed to a durability of 2600 hits until failure with Ti6-4 alloy as the faceplate material.

Thus, the invention provides, among other things, a method of forming agolf club head assembly. Although the invention has been described indetail with reference to certain preferred embodiments, variations andmodifications exist within the scope and spirit of one or moreindependent aspects of the invention as described.

Clause 1. A method of forming a golf club head assembly, the methodcomprising:

aligning a faceplate with a recess of a club head;

welding the faceplate to the club head;

after welding the faceplate, heating the club head and the faceplate toat least a solvus temperature of the faceplate for a predeterminedamount of time; and

after heating the club head and the faceplate, allowing the club headand the faceplate to cool in an inert gas.

Clause 2. The method of clause 1, further comprising forming thefaceplate from an α-β titanium alloy.

Clause 3. The method of clause 1, wherein welding the faceplate includesa pulse plasma welding process.

Clause 4. The method of clause 1, providing a faceplate with a minimumthickness of 0.7 mm.

Clause 5. The method of clause 1, wherein heating the club head and thefaceplate includes heating the club head and the faceplate for between 1hour and 6 hours.

Clause 6. The method of clause 5, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between400° C. and 630° C.

Clause 7. The method of clause 6, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between475° C. and 625° C. for between 1 hour and 6 hours.

Clause 8. The method of clause 7, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between475° C. and 550° C. for between 4 hours and 6 hours.

Clause 9. The method of clause 8, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between475° C. and 500° C. for between 4 hours and 6 hours.

Clause 10. The method of clause 7, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between550° C. and 625° C. for between 1 hour and 2 hours.

Clause 11. The method of clause 10, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 575° C. and 625° C. for between 1 hour and 2 hours.

Clause 12. A method of forming a golf club head assembly, the methodcomprising:

providing a faceplate formed from an α-β titanium alloy, the alloyhaving a solvus temperature;

aligning the faceplate with a recess of a club head;

welding the faceplate to the club head;

after welding the faceplate, heating the club head and the faceplate toa temperature that is greater than the solvus temperature of thefaceplate for a predetermined amount of time; and

after heating the club head and the faceplate, allowing the club headand the faceplate to air cool.

Clause 13. The method of clause 11, wherein welding the faceplateincludes a pulse plasma welding process.

Clause 14. The method of clause 11, wherein heating the club head andthe faceplate includes heating the club head and the faceplate forbetween 1 hour and 6 hours.

Clause 15. The method of clause 13, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 400° C. and 630° C.

Clause 16. The method of clause 15, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 625° C. for between 1 hour and 6 hours.

Clause 17. The method of clause 16, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 550° C. for between 4 hours and 6 hours.

Clause 18. The method of clause 17, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 500° C. for between 4 hours and 6 hours.

Clause 19. The method of clause 15, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 550° C. and 625° C. for between 1 hour and 2 hours.

Clause 20. The method of clause 19, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 575° C. and 625° C. for between 1 hour and 2 hours.

Clause 21. The method of clause 12, wherein the faceplate is formed fromone of Ti 6-4 and Ti-9S (or T-9S).

Clause 22. The method of clause 21, wherein the inert gas is selectedfrom the group consisting of nitrogen (N), argon (Ar), helium (He), neon(Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof.

Clause 23. The method of clause 22, wherein the inert gas is nitrogen(N) or argon (Ar) or a compound gas thereof.

Clause 24. A method of forming a golf club head assembly, the methodcomprising: (a) providing a faceplate formed from an α-β titanium alloy,the α-β titanium alloy comprising between 6.5 wt % to 8.5 wt % aluminum(Al), 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt % or less oxygen (O),and 0.20 wt % or less silicon (Si); (b) aligning the faceplate with arecess of a club head; (c) welding the faceplate to the club head; (d)heating the club head and the faceplate to a temperature that is greaterthan the solvus temperature of the faceplate for a predetermined amountof time; and (e) allowing the club head and the faceplate to cool in aninert gas, wherein step (d) is performed between 525° C. and 625° C. forbetween 1 hour and 6 hours.

Clause 25. The method of clause 24, wherein the α-β titanium alloyfurther comprises 0.30 wt % or less iron (Fe), 0.08 wt % or less carbon(C), 0.05 wt % or less nitrogen (N), trace molybdenum (Mo), trace tin(Sn), and the remaining weight percent is titanium (Ti).

Clause 26. The method of clause 24, wherein the welding of step (c)includes a pulse plasma welding process.

Clause 27. The method of clause 24, wherein the inert gas of step (e) isselected from the group consisting of nitrogen (N), argon (Ar), helium(He), neon (Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof.

Clause 28. The method of clause 27, wherein the inert gas is nitrogen(N) or argon (Ar).

Clause 29. The method of clause 24, wherein the faceplate of step (a)has a minimum thickness of 0.7 mm.

Clause 30. The method of clause 24, wherein step (d) includes heatingthe club head and the faceplate between 550° C. and 625° C. for between1 hour and 2 hours.

Clause 31. The method of clause 30, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 575° C. and 625° C. for between 1 hour and 2 hours.

Clause 32. A method of forming a golf club head assembly, the methodcomprising: providing a faceplate formed from an α-β titanium alloy, theα-β titanium alloy comprising between 6.5 wt % to 8.5 wt % aluminum(Al), 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt % or less oxygen (O),0.20 wt % or less silicon (Si), 0.30 wt % or less iron (Fe), 0.08 wt %or less carbon (C), 0.05 wt % or less nitrogen (N), trace molybdenum(Mo), trace tin (Sn), and the remaining weight percent is titanium (Ti);aligning the faceplate with a recess of a club head; welding thefaceplate to the club head; after welding the faceplate, heating theclub head and the faceplate to a temperature that is greater than thesolvus temperature of the faceplate for a predetermined amount of time;and after heating the club head and the faceplate, allowing the clubhead and the faceplate to cool in an inert gas environment.

Clause 33. The method of clause 32, wherein welding the faceplateincludes a pulse plasma welding process.

Clause 34. The method of clause 32, wherein heating the club head andthe faceplate includes heating the club head and the faceplate forbetween 1 hour and 6 hours.

Clause 35. The method of clause 34, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 400° C. and 630° C.

Clause 36. The method of clause 35, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 625° C. for between 1 hour and 6 hours.

Clause 37. The method of clause 36, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 550° C. for between 4 hours and 6 hours.

Clause 38. The method of clause 37, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 475° C. and 500° C. for between 4 hours and 6 hours.

Clause 39. The method of clause 35, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 550° C. and 625° C. for between 1 hour and 2 hours.

Clause 40. The method of clause 39, wherein heating the club head andthe faceplate includes heating the club head and the faceplate tobetween 575° C. and 625° C. for between 1 hour and 2 hours.

Clause 41. The method of clause 32, wherein the inert gas of step (e) isselected from the group consisting of nitrogen (N), argon (Ar), helium(He), neon (Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof.

Clause 42. The method of clause 41 wherein the inert gas is nitrogen (N)or argon (Ar).

Clause 43. The method of clause 32, wherein the faceplate of step (a)with a minimum thickness of 0.7 mm.

Clause 44. A golf club head comprising: a crown, a sole; a toe end; aheel end; a recess positioned between the crown and the sole, andbetween the toe and heel ends; a hosel positioned adjacent to the heelend; a faceplate that is aligned with the recess and welded to the clubhead, the faceplate having a bulge curvature extending between the heelend and the toe end, the faceplate including an α-β titanium alloycomprising between 6.5 wt % to 8.5 wt % aluminum (Al), 1.0 wt % to 2.0wt % vanadium (V), 0.20 wt % or less oxygen (O), 0.20 wt % or lesssilicon (Si), 0.30 wt % or less iron (Fe), 0.08 wt % or less carbon (C),0.05 wt % or less nitrogen (N), trace molybdenum (Mo), trace tin (Sn),and the remaining weight percent is titanium (Ti); wherein after thefaceplate is welded to the club head, the club head and the faceplateare heated between 525° C. and 625° C. for between 1 hour and 6 hour;and allowed to cool in an inert gas.

The invention claimed is:
 1. A method of forming a golf club headassembly, the method comprising: (a) providing a faceplate formed froman α-β titanium alloy, the α-β titanium alloy comprising between 6.5 wt% to 8.5 wt % aluminum (Al), 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt% or less oxygen (O), and 0.20 wt % or less silicon (Si); (b) aligningthe faceplate with a recess of a club head; (c) welding the faceplate tothe club head; (d) heating the club head and the faceplate to atemperature that is greater than the solvus temperature of the faceplatefor a predetermined amount of time; and (e) allowing the club head andthe faceplate to cool in an inert gas, wherein step (d) is performedbetween 525° C. and 625° C. for between 1 hour and 6 hours.
 2. Themethod of claim 1, wherein the α-β titanium alloy further comprises 0.30wt % or less iron (Fe), 0.08 wt % or less carbon (C), 0.05 wt % or lessnitrogen (N), trace molybdenum (Mo), trace tin (Sn), and the remainingweight percent is titanium (Ti).
 3. The method of claim 1, wherein thewelding of step (c) includes a pulse plasma welding process.
 4. Themethod of claim 1, wherein the inert gas of step (e) is selected fromthe group consisting of nitrogen (N), argon (Ar), helium (He), neon(Ne), krypton (Kr), and xenon (Xe) or a compound gas thereof.
 5. Themethod of claim 4, wherein the inert gas is nitrogen (N) or argon (Ar).6. The method of claim 1, wherein the faceplate of step (a) has aminimum thickness of 0.7 mm.
 7. The method of claim 1, wherein step (d)includes heating the club head and the faceplate between 550° C. and625° C. for between 1 hour and 2 hours.
 8. The method of claim 7,wherein heating the club head and the faceplate includes heating theclub head and the faceplate to between 575° C. and 625° C. for between 1hour and 2 hours.
 9. The method of claim 1, wherein the faceplate ofstep (a) with a minimum thickness of 0.7 mm.
 10. A method of forming agolf club head assembly, the method comprising: providing a faceplateformed from an α-β titanium alloy, the α-β titanium alloy comprisingbetween 6.5 wt % to 8.5 wt % aluminum (Al), 1.0 wt % to 2.0 wt %vanadium (V), 0.20 wt % or less oxygen (O), 0.20 wt % or less silicon(Si), 0.30 wt % or less iron (Fe), 0.08 wt % or less carbon (C), 0.05 wt% or less nitrogen (N), trace molybdenum (Mo), trace tin (Sn), and theremaining weight percent is titanium (Ti); aligning the faceplate with arecess of a club head; welding the faceplate to the club head; afterwelding the faceplate, heating the club head and the faceplate to atemperature that is greater than the solvus temperature of the faceplatefor a predetermined amount of time; and after heating the club head andthe faceplate, allowing the club head and the faceplate to cool in aninert gas environment.
 11. The method of claim 10, wherein welding thefaceplate includes a pulse plasma welding process.
 12. The method ofclaim 10, wherein heating the club head and the faceplate includesheating the club head and the faceplate for between 1 hour and 6 hours.13. The method of claim 10, wherein heating the club head and thefaceplate includes heating the club head and the faceplate to between400° C. and 630° C.
 14. The method of claim 13, wherein heating the clubhead and the faceplate includes heating the club head and the faceplateto between 475° C. and 625° C. for between 1 hour and 6 hours.
 15. Themethod of claim 14, wherein heating the club head and the faceplateincludes heating the club head and the faceplate to between 475° C. and550° C. for between 4 hours and 6 hours.
 16. The method of claim 15,wherein heating the club head and the faceplate includes heating theclub head and the faceplate to between 475° C. and 500° C. for between 4hours and 6 hours.
 17. The method of claim 13, wherein heating the clubhead and the faceplate includes heating the club head and the faceplateto between 550° C. and 625° C. for between 1 hour and 2 hours.
 18. Themethod of claim 17, wherein heating the club head and the faceplateincludes heating the club head and the faceplate to between 575° C. and625° C. for between 1 hour and 2 hours.
 19. The method of claim 10,wherein the inert gas of step (e) is selected from the group consistingof nitrogen (N), argon (Ar), helium (He), neon (Ne), krypton (Kr), andxenon (Xe) or a compound gas thereof.
 20. The method of claim 19,wherein the inert gas is nitrogen (N) or argon (Ar).
 21. A golf clubhead comprising: a crown, a sole; a toe end; a heel end; a recesspositioned between the crown and the sole, and between the toe and heelends; a hosel positioned adjacent to the heel end; a faceplate that isaligned with the recess and welded to the club head, the faceplatehaving a roll curvature positioned between the crown and the toe end,the faceplate including an α-β titanium alloy comprising between 6.5 wt% to 8.5 wt % aluminum (Al), 1.0 wt % to 2.0 wt % vanadium (V), 0.20 wt% or less oxygen (O), 0.20 wt % or less silicon (Si), 0.30 wt % or lessiron (Fe), 0.08 wt % or less carbon (C), 0.05 wt % or less nitrogen (N),trace molybdenum (Mo), trace tin (Sn), and the remaining weight percentis titanium (Ti); wherein after the faceplate is welded to the clubhead, the club head and the faceplate are heated between 525° C. and625° C. for between 1 hour and 6 hour, and allowed to cool in an inertgas.